1. Field of the Invention
The present invention relates to an identification method of determining whether a data point distribution area is distributed in a specific determination area and a recording medium storing a program causing a computer to execute the identification method.
2. Description of the Related Art
Semiconductor devices (a.k.a chips) are manufactured through various processes. Various defects during the various processes may cause the degradation of the quality and the decrease of the yield rate of the semiconductor devices. In this regard, to improve and stabilize the yield rate, the pattern defect inspection and the particle (contamination) inspection are conducted after a predetermined process to check the existence of the defects.
Further, in each process, after the pattern is formed, the electric characteristic test (wafer test) is performed on each chip on the wafer to detect the defects.
Of the information obtained as a result of inspection or test, there is information indicating defects on the wafer and a distribution of defective chips. In the following, the defects on the wafer or the distribution of defective chips is called “defect distribution”.
The defect distribution may be classified into two types: in one type, the defect distribution is substantially uniformly distributed across the wafer without being concentrated on a specific area on the wafer; and in the other type, the defect distribution is unevenly distributed and may be concentrated on a specific area on the wafer. The defects in the former type where the defects are evenly distributed may be called random defects. On the other hand, the defects in the latter type where the defects are concentrated on a part of the wafer may be called clustering defects.
The defect distribution in which the defects are concentrated (hereinafter “concentrated defect distribution”) is mainly caused by the problems in the manufacturing processes, manufacturing apparatuses and the like. Because of this feature, by investigating the manufacturing processes, the manufacturing apparatuses, and the like, the cause of the lowering of the yield rate may be detected.
As one example of using the information, a status of the defect distribution on a wafer is analyzed first, and based on the analysis, the cause of the defects in the manufacturing processes, manufacturing apparatuses, and the like is estimated (see, for example, Patent Documents 1 and 2).
Patent document 1 describes a method of specifying a cause of defect by grouping (classifying) the wafer based on a status of the clustered defect distribution and then determining whether the status is similar to a known pattern of the defect distribution.
Patent document 2 describes a method of classifying the categories of the defects based on the distribution status of the defect into repetitive defects, congestion defects, liner defects, ring/lump defects, random defects and the like.
Generally, the position of the chip is expressed using the X axis and the Y axis. To express the information of data group indicating the chip positions on a wafer, those data are expressed on the XY rectangular coordinate plane.
As described above, the concentrated defect distribution in the manufacturing process of manufacturing the semiconductor devices may be caused by the problems on the manufacturing apparatus and the like. Therefore, when the concentrated defect distribution is detected, a defective process may be estimated by collecting the information of lots of the wafers having a similar status of the defect distribution and then investigating the relevant recorded data indicating, for example, which processing apparatus was used and when the process was performed in the manufacturing processes.
In this case, whether the defective distribution is similar to the known pattern of the defect distribution is determined depending on whether the defective distribution exists on a specific area on a wafer (coordinate plane).
In the methods of Patent Documents 1 and 2, the position of the defective distribution is specified by processing data indicating the positions of the defects and defective chips. However, all of the data points of the defective distribution have respective data (e.g., positional information). Namely, under a status where all the data points included in the data point distribution area on the coordinate plane have the respective data, it is determined whether the data point distribution area is distributed on a specified determination area set on the coordinate plane.    Patent Document 1: Japanese Patent Application Publication No. 06-61314    Patent Document 2: Japanese Patent No. 4038356